Method and associated apparatus for detecting minor traumatic brain injury

ABSTRACT

Minor traumatic brain injury is detected by operating (a) an image generator for presenting a visual stimulus having a predetermined movement across a visual field of a subject and (b) a sensor device for monitoring fast eye movement of the subject while the subject views the stimulus. The sensor device generates a signal encoding the subject&#39;s eye position. A computer or microprocessor operatively connected to the sensor device is configured for determining a parametric value for the fast eye velocity component.

BACKGROUND OF THE INVENTION

The present invention relates to a method for detecting brain injury.More particularly, this invention relates to a noninvasive andatraumatic method for detecting minor traumatic brain injury. Thisinvention also relates to an associated apparatus.

It is well known that certain contact sports frequently result in injuryto the participants. One kind of potential injury that frequently goesundetected is minor traumatic brain injury. (Major traumatic braininjury can hardly fail to be detected even upon cursory inspection.) Asminor traumatic brain injury heretofore has been undetectable, theinjured sports participant is usually sent back into the fray withouttreatment of any sort. The injury may be then compounded by further headtrauma from forceful engagements ensuing on the field or in the arena.

Minor traumatic brain injury may also be sustained during militaryconflict. Again, owing to an inability to detect the injury, the injuredcombatants are returned to the front lines, with the possibility ofadditional injury to the brain, as well as other organs.

The resulting costs to society are obvious. Multiple minor traumaticbrain injuries can give rise to permanent dysfunction and also majorinjury and the necessity for extensive treatment expenses.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a method and/or anapparatus for facilitating, if not enabling, the detection of minortraumatic brain injury.

It is another, more particular, object of the present invention toprovide such a method and/or apparatus for facilitating, if notenabling, on site detection of minor traumatic brain injury.

It is a further particular object of the present invention to providesuch a method and/or an apparatus, which permits a test to be donequickly and which is easy to use.

It is a related object of the present invention to provide such a methodand/or an apparatus which does not require the services of trainedmedical personnel.

These and other objects of the present invention will be apparent fromthe drawings and descriptions herein. It is to be noted that any singleembodiment of the invention may not achieve all of the objects of theinvention, but that every object is attained by at least one embodiment.

SUMMARY OF THE INVENTION

A method for detecting minor traumatic brain injury comprises, inaccordance with the present invention, presenting to a subject a visualstimulus having a predetermined direction and speed of movement acrossthe visual field of the subject and monitoring the subject's eyemovement while the subject views the stimulus, where the eye movementincludes a voluntary or a reflexive slow eye velocity component and aninvoluntary fast eye velocity (reset) component. The slow eye velocitycomponent corresponds, and is responsive, to the predetermined movementof the visual stimulus, while the fast eye velocity component istypically an involuntary reset movement in an opposite direction (e.g.,retrograde). The monitoring of eye movement includes detecting the fasteye velocity component. Detecting the fast eye component preferablyentails sensing the amount of peak velocity movement of the eye, as afunction of time. The method further comprises determining a parameterof the detected fast eye velocity component and comparing the determinedparameter with a predetermined reference value to determine whether thesubject has incurred minor traumatic brain injury.

It is contemplated that the method of the present invention is mainlyperformed automatically. Thus, the monitoring of eye movement mayinclude or be done by a sensor device such as a camera. A digitalcomputer may be operatively connected to the camera, so that themonitoring of eye movement includes operating the digital computer, forinstance, to carry out a pattern recognition process and/or a filteringprocess to identify the fast eye velocity movement.

The parameter of fast eye movement may be a velocity or speed inclusiveof peak velocity in degrees per second as a function of the amplitudetraveled in the movement. In that case, the monitoring of eye movementincludes measuring an amplitude or angular distance of a fast eyevelocity movement and dividing the measured or angular distance by theduration of the fast eye movement and the amount of movement. Thus, theunits of the magnitude may be degrees per unit time per distancetraveled.

Alternatively, the parameter may be otherwise characteristic of the fasteye movement component. For instance, the parameter may constitute astatistical measure of a distribution of fast eye movement amplitudes ora distribution of fast eye movement velocities detected during adiagnostic evaluation test. In that case, determining the parametricstatistical value includes measuring amplitude or angular distance offast eye movement or fast eye movement velocity of multiple instances ofthe fast eye velocity component and determining a distribution ofamplitudes or velocities. A statistical measure of the distribution isgenerated by the computer or microprocessor using conventionalstatistics algorithms. The predetermined reference value may be astatistical reference value of the same kind as the statistical measure.The statistical value utilized may be a mean, a median, a mode, astandard deviation measure, and/or some combination of these.Alternatively, the measured parameter may be the number of fast eyemovements counted during a predetermined interval.

The predetermined reference value may alternatively take the form of ameasured value peculiar to the subject and derived from tests on thesubject prior to physical impact or trauma possibly giving rise to minortraumatic brain injury.

Typically, the stimulus is a striped pattern, specifically, alternatingdark and bright vertical bands that move to the right or left. When thestimulus motion is to the right, the fast eye movement is typically tothe left and vice versa. What happens generally is that subject fastenshis or her focus on the center of the visual field and counts thestripes as they go by. The eye voluntarily registers the bands at aspeed consistent with movement across the visual field and involuntarilybacktracks in a fast eye movement in the opposite direction, andregisters the next band to follow in a slow eye velocity movement. Thispattern of alternating fast and slow movements may continueindefinitely, as long as the stimulus is passing across the displayscreen. The degree or amount that the eye travels during the fast andslow eye movements however differs although the velocity of the stimulusdoes not.

A plot of eye position/movement may be plotted along the ordinate of agraph, with the abscissa representing time or duration of the stimulus.The resulting plot takes the form of a saw tooth curve, with shallowline segments corresponding to slow eye movement and intercalated steepline segments corresponding to fast eye movements. The slopes of theline segments increase as the eye movement velocity increases.Typically, the saw tooth is irregular with teeth of varying heights,owing to variation in the amplitudes or angular distances traversed bythe subject's eye as fast and slow eye movements during a stimuluspresentation. As indicated above, these “heights” may be groupedaccording to magnitude and organized into a distribution of amplitudestraveled by each fast eye movement. The distribution can be subjected tovarious statistical parsing, with numerical statistical values beingused for comparison with reference values that are derived bystatistical measurement of multiple normal and traumatically braininjured test subjects.

The measured parameter may simply be peak fast eye movement velocity.During one stimulus viewing, multiple comparisons of the measuredparameter, magnitude of fast eye velocity per amount of eye movement,may be made with respect to one or more predetermined referencevalues—which are standards or reference thresholds for fast eye movementfor degree of eye movement. One measures the peak fast eye movementvelocity in each successive fast eye movement and compares the measuredvelocity associated with distance traveled each time with thepredetermined numerical reference value or threshold. Alternatively, onemight select the largest or peak value of eye velocity for each ofplurality of ranges of fast eye movement amplitudes (e.g., short,medium, and long) and compare each peak value with a respectivepredetermined numerical threshold. In each of these cases, the diagnosisof potential brain trauma could depend on the percentage of comparisonswhere the measured eye velocity falls below a reference or thresholdvalue.

It is possible to use the method and apparatus of the present inventionto monitor brain health or integrity using a parameter of eye movementversus eye velocity with analysis of the degree of uniformity among theamplitudes or angular distances of the fast eye movements. Greateruniformity might indicate a potential injury. Conversely, a substantialvariation in the amplitudes would indicate an undamaged or healthybrain.

Alternatively, one might construct a graph with the abscissa or x-axis,for example, as the amplitude or degree of eye movement and the ordinateor y-axis the velocity for that movement. (Generally, fast eye movementvelocity varies as a function of amplitude or distance—the greater theangular distance through which the eye moves, the more velocity the eyecan build up during its transit of that angular distance.) If fast eyevelocity falls below 2 standard deviations of norms for any degree ofmovement, that can be taken as an indicator of potential brain trauma.

The multiple amplitudes of fast eye movement are collected by genericdigital processing circuits of a microprocessor that may be configuredthrough software to analyze each single response, each “triangle” of thesaw tooth eye-movement graph of amount of eye position moved vs. timerequired for the movement, to thereby identify the distances traveledper time elapsed for that travel during the fast phase. Themicroprocessor may be configured to execute a filter set to screen outeye movement velocities that are too slow to be a fast eye velocity andto screen out eye movement amplitudes of an inappropriate length for afast eye velocity movement.

Amplitudes or magnitudes of fast eye movement vary given that the eyemay travel a different length/distance in each eye movement. Asindicated above, these magnitudes or amplitudes of fast eye movement maybe detected and grouped into various discrete sets, for instance, 6°,8°, 10°, 12°. Measurements between 7° and 9° are placed in the 8° set,while measurements between 9° and 11° are sorted into the 10° set, etc.The selected brain-injury index or parameter may be the degree ofvariation among the different amplitudes of fast eye movement. Ifgreater uniformity indicates a potential injury. then standard deviationis a measurement of uniformity and can be used as a numericalstatistical value for calculation and comparison.

Where the parameter of fast eye movement being utilized for brain traumadiagnosis is velocity or speed, per amount of eye movement, themagnitude of the velocity may be determined by operating the digitalcomputer or microprocessor to carry out an arithmetic calculation—avelocity calculation. As mentioned above, a measured amplitude orangular distance of fast eye movement is divided by the time or durationof the fast eye movement. Again, multiple velocity magnitudes arecomputed for a single transit of the stimulus across the display screen,one for each fast eye movement.

As indicated above, the measured velocities of fast eye movement may becollected into a distribution (essentially an encoded bar graph) andsubjected to statistical analysis for purposes of comparison with apredetermined standard. Thus, instead of individual velocities beingseparately compared with one or more reference velocities, a calculatedmean, deviation, mode median, etc., is compared with an analogousreference statistic. An amplitude distribution rather than a velocitydistribution may be used.

A distribution of fast eye movement amplitudes or velocities may be usedas a basis for statistical evaluation inasmuch as magnitudes of fast eyemovement velocity vary given that the eye may travel a differentlength/distance in each eye movement. Velocity varies with the distancetraveled in degrees. Also, velocity varies as between a healthy personand a brain injured patient, for the same distance of eye travel. Onewould have a “normogram” of peak velocities for each distance/amount ofeye movement and determine whether a test subject's peak velocities werewithin 2 standard deviations of the norms. If test subject's peakvelocities fall below the norms, that is an indication of brain stemdysfunction. Alternately, one would compare a person's responses afteran injury to their response for the above parameters prior to injury todetermine if the response has changed significantly consistent with amTBI.

Where the sensor device and the computer or microprocessor are housed ina casing, the casing may be provided with a display, and the presentingof the stimulus includes operating the computer or microprocessor toprovide the stimulus as a moving image on the display.

The casing may take the form of a head mounted device, such as glassesor goggles, in which case the method further comprises removablyattaching the casing to a head of the subject prior to the presenting ofthe stimulus.

The computer or microprocessor may be hard wired or programmed forautomatically comparing a measured eye-movement magnitude or acalculated statistical value with a predetermined numerical referencevalue. In an alternative arrangement, computations are performed by acomputer at a remote location. In that case the determining of the eyevelocity magnitude or fast eye movement parameter includes transmittingeye movement data over a computer network and receiving a computed eyemovement velocity and/or statistical value in return over the computernetwork. The comparison of an eye movement parameter with apredetermined reference value may also be performed at a remote locationby another computer. In that event, the result of the comparison may betransmitted back to the on site digital computer or microprocessor,either alone or together with a computed magnitude of the fast eyevelocity parameter.

Preferably, however, both the determination of a fast eye movementparameter and the comparison thereof with a predetermined referencevalue or threshold are automatically performed through the operation ofa programmed electronic device on site. This ensures that an evaluationmay be made at any time and any place, regardless of access to awireless or other network. An apparatus for detecting minor traumaticbrain injury comprises, in accordance with the present invention, (a) animage generator for presenting a visual stimulus having a predeterminedmovement across the visual field of a subject and (b) a sensor devicefor monitoring movement of an eye of the subject while the subject viewsthe stimulus. Again, the eye movement includes a voluntary slow eyevelocity component and an involuntary fast eye velocity component, wherethe slow eye velocity component directly tracks the predeterminedmovement of the visual stimulus and the fast eye velocity component istypically counter to the direction of movement of the stimulus. Thesensor device generates a signal encoding eyeball position. Theapparatus further includes a computer or microprocessor operativelyconnected to the sensor device, the computer or microprocessor beingconfigured for determining a parameter, preferably a magnitude ornumerical value, for the fast eye velocity component. Typically, theparameter is an angular speed, in degrees per second, or a statisticalvalue of an amplitude or velocity distribution. In the case of angularspeed the calculation for the magnitude is the distance traveled dividedby time elapsed during that travel beginning from initiation to end ofeye movement, for each different amount/amplitude of eye movement.Alternatively, a measure of the homogeneity or lack thereof ofdistribution of velocities/amplitudes across multiple fast eye movementswill distinguish between normal and brain injury.

Pursuant to another feature of the present invention, the computer ormicroprocessor is further configured to compare the determined fast eyemovement parameter with a predetermined reference value to determinewhether the subject has incurred minor traumatic brain injury.

In accordance with an additional feature of the present invention, wherethe sensor device is a camera, the computer or microprocessor isconfigured for executing a pattern recognition process and a filteringprocess to identify the fast eye velocity movement. The camera may be anoptical camera and/or an infrared camera.

Pursuant to a further feature of the present invention, the sensordevice and the computer or microprocessor are housed in (i.e., attachedto) a casing, and the casing is provided with a display. In that event,the computer or microprocessor is operatively connected to the displayfor operating the display to provide the stimulus as a moving image onthe display. The casing may be provided with an input capability, suchas a keyboard implemented either via mechanical keys or a touch screenon the display. The input device enables the user to vary the stimulus,for instance, the width and/or contrast and/or speed of movement ofvertical bands on the display. The display functions in part as agraphical user interface, providing feedback and options to the user,which the user selects via the keyboard or other input functionality.

Preferably, the casing has a hand-holdable configuration and size. Thecasing may be a notebook sized device or a frame such as eyeglasses orgoggles mountable to the head of the subject over the subject's eyes. Inthat case, a headband or cap or other coupling element is provided forremovably attaching the casing to a head of the subject.

In accordance with a supplemental feature of the present invention, thecomputer or microprocessor is configured for transmitting eye movementdata over a computer network and receiving a computed eye movementvelocity or diagnostic result in return over the computer network.

A method and/or an apparatus in accordance with the present inventionfacilitates, if not enables, the detection of minor traumatic braininjury. A test or measurement may be performed on location, therebyenabling an informed decision as to whether a potentially injured sportsplayer or soldier is in fact brain injured and should be at leasttemporarily withdrawn from continued participation in the physicalconflict. A method and/or apparatus in accordance with the presentinvention is easy and quick to use. The invention may be used withoutrequiring the services of trained medical personnel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a device in accordance with the presentinvention for detecting potential minor traumatic brain injury.

FIG. 2 is a block diagram depicting components of a computer ormicroprocessor shown in FIG. 1, as well as other elements shown in FIG.1.

FIG. 3 is a block diagram depicting components of a fast eye movementdetection unit shown in FIG. 2.

DETAILED DESCRIPTION

As depicted in FIG. 1, an apparatus 10 for detecting minor traumaticbrain injury comprises a display 12 for presenting a visual stimulushaving a predetermined movement across a visual field of a subject.Display 12 is controlled by a microprocessor or digital computer 14,which functions in part, together with the display, as an imagegenerator. The visual stimulus can take any form that is perceptible bya subject and that can move across the display screen. Typically, thevisual stimulus takes the form of a series of vertically oriented barsor stripes that move laterally across the display screen, i.e., to theright or the left. Alternatively, the visual stimulus might take theform of a spot or icon or a series of spots or icons, or other graphicrepresentations.

Apparatus 10 further comprises a sensor device 16 for monitoringmovement of an eye of the subject while the subject views the stimuluson display 12. Sensor device 16 typically takes the form of an opticalor infrared camera. Camera 16 and display 12 are mounted to a frame 18,which may be a casing of a handheld or hand-holdable electronic devicesuch as a notebook computer. In that event, camera 16 is disposed on thesame side of the frame or casing 18 as display 12.

Alternatively, frame or casing 18 may be goggles or an eyeglass framewith a coupling or mounting element 20 such as eyeglass arms or a strapor band for removably attaching the eyeglasses to the head of anindividual subject. Products such as eyeglasses with incorporatedcomputers and visual displays on the lenses are known in the art.

The eye movement of a subject attending to the moving visual stimulus ondisplay 12 includes a voluntary slow eye velocity component and aninvoluntary fast eye velocity component. Sensor device or camera 16generates a signal encoding the position of the subject's eye at leastduring the fast eye velocity component. The slow eye velocity componentdirectly tracks the predetermined movement of the visual stimulus. Thespeed of the fast eye component, if below a certain threshold, mayindicate abnormal brain function possibly occasioned by minor traumaticbrain injury.

Computer or microprocessor 14 is operatively connected to sensor deviceor camera 16, the computer or microprocessor being configured fordetermining a parameter of the fast eye velocity component. Preferably,computer or microprocessor 14 is configured (e.g., hard wired orprogrammed by software) to determine a magnitude of the parameter. Theterm “magnitude” is used herein to denote a numerical value, positive ornegative, characteristic of fast eye movement and used for comparisonwith another numerical value, namely, a reference value or thresholdthat is either experimentally determined to be statistically indicativeof minor traumatic brain injury or characteristic of the pre-injurystate of the particular subject. In the latter case, a significantdeviation from pre-injury values indicates possible or probable minortraumatic brain injury. A calculated fast eye movement magnitude isderived from detected fast eye movement and may be of any eye movementparameter or mathematical relationship that is determined to beindicative of brain injury. For instance, the parameter magnitude may bea statistical measure of a distribution of fast eye movement amplitudes(or velocities) detected during a diagnostic evaluation session. In thatcase, determining the parameter magnitude includes measuring amplitudeor angular distance of fast eye movement (or fast eye movement velocity)during multiple instances of the fast eye velocity component anddetermining a distribution of amplitudes (or velocities). A statisticalmeasure of the distribution is generated by the computer ormicroprocessor using conventional statistics algorithms. Thepredetermined reference value may be a statistical reference value ofthe same kind as the statistical measure. The statistical value utilizedmay be a mean, a median, a mode, a standard deviation measure, and/orsome combination of these. Alternatively, the measured parameter may bethe number of fast eye movements counted during a predeterminedinterval.

The predetermined reference value may alternatively take the form of ameasured value peculiar to the subject and derived from tests on thesubject prior to physical impact or trauma possibly giving rise to minortraumatic brain injury.

Computer or microprocessor 14 may also be configured or programmed forcomparing the determined eye velocity parameter, magnitude, or statisticwith a predetermined threshold reference value stored in a memory 22, tothereby obtain an automated diagnosis of potential minor traumatic braininjury. Alternatively, the computation of a selected fast eye velocityparameter, magnitude, or statistic and the diagnostic comparison with athreshold reference value may be performed by a remote computer (notillustrated) with which computer or microprocessor 14 communicates via atransceiver unit 24, for instance, a dedicated hard-wired communicationslink or a wireless communications link connecting to the Internet or aprivate computer network.

Where the monitored eye movement parameter is fast eye movementvelocity, the comparison of the measured velocity magnitude with apredetermined numerical value—which is a standard or referencethreshold—may occur multiple times during one stimulus viewing. It ispossible, for instance, to measure the fast eye movement velocity foreach successive fast eye movement and compare the measured velocity eachtime with the predetermined numerical reference value or threshold.

Alternatively, instead of a single numerical threshold value, one mightuse a plurality of numerical threshold values each assigned to aparticular band of eye movement amplitudes. Each measured fast eyemovement velocity is then compared with a threshold value that dependsis selected in accordance with the amplitude of the respective fast eyemovement. Generally, small amplitudes will have smaller eye speedthresholds or reference values.

An alternative measured parameter may be normalized eye movementvelocity, for instance, the velocity of a fast eye movement divided bythe distance traveled during that fast eye movement.

In another alternative approach, one might select the largest or peakvalue of eye velocity for each of plurality of ranges of fast eyemovement amplitudes (e.g., short, medium, and long) and compare eachpeak value with a predetermined numerical threshold allotted to therespective amplitude range. When multiple comparisons are made fortesting a single subject, the diagnosis of potential brain trauma coulddepend on the percentage of positives, i.e., comparisons where themeasured eye velocity (whether individual or peak) falls below areference or threshold value.

Frame or casing 18 may be provided with an input capability, such as akeyboard 26 implemented either via mechanical keys or a touch screen onthe display 12. In that case, display 12 functions in part as agraphical user interface, providing feedback and options to the user,which the user selects via keyboard 26 or other input functionality.Options may include characteristics of the stimulus such as size, shape,contrast, and direction and speed of movement. Other options may includethe kind of parameter that is to be measured and compared with athreshold. As indicated above, possible parameters include fast eyemovement velocity, normalized fast eye movement velocity, anddistribution of fast eye movement amplitudes. In the case of adistribution of fast eye movement amplitudes, computer or microprocessor14 is hard wired or programmed to analyze the distribution of beatamplitudes per stimulus. A stimulus is typically a fixed-velocitystimulus that persists for a predetermined time interval, for instance,a stimulus of 60°/sec that continue for 30 seconds A distribution offast eye movement amplitudes or velocities may be numericallycharacterized by one or more selected statistical measures such as mean,median, mode, deviation (or spread) or by total number of fast eyemovements (beats) within a given interval.

Where peak fast eye movement velocity is the selected parameter,additional options include the number and types of comparisons that areundertaken. Comparison with a threshold might be undertaken for eachfast eye movement during the course of a stimulus presentation.Alternatively, comparisons might be undertaken for only those fat eyemovements where the eye movement amplitude exceeds a preselected value.

As illustrated in FIG. 2, computer or microprocessor 14 typicallycomprises a communications and setup unit 28 which is connected tokeyboard 26 and to display 12 for interfacing with a user for purposesof calibration and the selection of operating parameters such asstimulus shape, size, and speed and direction of movement. To that end,communications and setup unit 28 is connected to a stimulus generator 30which is in turn connected to display 12 for purposes of energizingselected pixels of the display to show a moving image.

Computer or microprocessor 14 also includes a fast eye amplitude orvelocity detection module 32 and a fast eye velocity calculation module34. Detection module 34 is connected at an input to communications andsetup unit 28 for receiving therefrom data pertaining to thecharacteristics of the stimulus, particularly the direction and speed ofstimulus movement. Detection module 32 is also connected at an input tosensor device or camera 16 for receiving therefrom electrically encodeddata pertaining to eye movement. Detection module 32 is connected tocalculation module 34 and provides eye movement data thereto.Calculation module 34 computes a magnitude of fast eye movement (e.g.,peak velocity or amplitude) depending on the data from detection module32.

Computer or microprocessor 14 also incorporates a comparator 36 which isconnected to calculation module 34 and memory 22 for comparing acontemporaneously calculated or determined fast eye movement velocity oramplitude magnitude from calculation module 34 with a predeterminedthreshold or reference value from memory 22. The result of thecomparison, indicative of normalcy or potential brain trauma, iscommunicated to the user via a diagnostics unit 38. Diagnostics unit 38may provide the user with a qualitative indication such as “traumaticbrain injury” or “light injury” or “normal.” Alternatively, diagnosticsunit 38 may provide the user with a numerical evaluation such as a fasteye movement statistic or a percentage indicating a likelihood of braininjury. The diagnosis may be communicated to the user via display 12.

Keyboard 26 may be used to initiate a measurement process. Severalmeasurements may be made automatically within the same diagnosticsession. For instance, the stimulus may be induced to travel across thedisplay 12 several times, with communications and setup unit 28signaling the beginning and end of each stimulus transit.

As illustrated in FIG. 3, detection module 32 may include a patternrecognition module 40 that identifies the fast eye velocity movement inpart by analyzing an image of the subject to detect the orientation(angular position) of the subject's eye. Detection module 32 mayadditionally include an eye movement-tracking module 42 that comparessuccessive eye orientations to detect a direction of movement of the eyeand to generate a track or path of eye movement. Pattern recognitionmodule 40 may further include a amplitude filter (not separatelyillustrated) that screens out eye movements of angular distances thatare too long or too short to be fast eye movements. Concomitantly,velocity calculation module 34 may include a velocity filter (notseparately illustrated) that screens out velocities that are too slow tobe a fast eye velocity. Computer or microprocessor 14 naturally includesa time base or clock signal generator (not shown) that may be includedin either detection module 32 or calculation module 34 or connectedthereto, for enabling velocity calculations.

As indicated above, computer or microprocessor 14 is optionallyconnected to a transceiver 24 for transmitting eye movement data over acomputer network and receiving a computed eye movement parameter ordiagnostic result in return over the computer network. Alternatively oradditionally, computer or microprocessor 14 may transmit the results ofdiagnostic testing over the computer network to a remote computer forreporting purposes.

Computer or microprocessor 14 may be configured for storing in memory 22the results of testing for any particular subject. This enablescomparison of contemporaneous fast eye velocity magnitudes with priormeasurements for any given individual subject. Of course, where computeror microprocessor 14 transmits the eye velocity results to a remotecomputer, the remote computer and personnel having access thereto mayperform the historical evaluations.

Prior to use of the above-described apparatus in monitoring a subjectfor potential undetected brain injury, there is an initial calibrationprocess that allows computer or microprocessor 14 to determine/measurethe amount of eye movement between fixed points of known distancebetween the points. The speed of eye movement is not a factor in thisanalysis. This calibration in turn permits subsequent calculations ofthe distance that the eye travels during testing which in turn, in thecontext of the time elapsed during the movement, permits calculation ofthe velocity of the eye movement.

What is being calibrated or quantified is the distance that the eyemoves during the test. In order to identify this amount, before the testsequence, the amount of eye movement in millimeters is ascertained asthe eye moves between a pair of fixed points placed so that the fixedpoints are separated by a desired distance (usually 20° visual angle).With the knowledge of how much eye movement occurs, measured inmillimeters, as the eye moves from one to another fixed point, that isto say across a known visual angle, one can subsequently deduce theamount of eye movement in degrees during the test.

It is to be noted that eye movement is detected by the actual amount ofmovement of landmarks on the eye. One approach is to capture an opticalsignal which is analyzed by computer to locate the iris-pupillaryinterface. This in turn permits detection of the center of the pupilcircle, which is used as one point of reference, a point that moves witheye movement, for the calculation of eye position. One additionalreference point on the eye is required to allow calculation of eyeposition. The optimal approach would have the second point not moveregardless of eye movement. This is achievable by utilizing the firstPurkinge image, the position of a reflected light pattern on the cornea.The light source to create this reflection can be infrared.

In a method for detecting minor traumatic brain injury, which may usethe apparatus disclosed hereinabove, one presents to a subject a visualstimulus such as a bar, stripe, dot, icon, or graphic representation, ora series of bars, stripes, dots, icons, or graphic representations,which moves along a predetermined path across a visual field of thesubject. Preferably, the stimulus is presented on a small electronicdisplay 12 such as that of a handheld electronic device (notebook,cellphone, personal digital assistant) or on the lenses of glasses orgoggles. In the latter case, the method further comprises removablyattaching the casing 18 to a head of the subject prior to the presentingof the stimulus on display 12.

Eye movement of the subject is monitored while the subject views thestimulus. As indicated above, eye movement typically includes avoluntary slow eye velocity component, which tracks the predeterminedmovement of the stimulus, and an involuntary fast eye velocitycomponent, which is particularly monitored for its rapidity. A user (whomay also be the subject) operates the measurement apparatus 10 todetermine a magnitude for the detected fast eye velocity component andto compare the determined magnitude or a derivative statistical measurewith a predetermined numerical value to determine whether the subjecthas incurred minor traumatic brain injury.

Preferably, the monitoring of eye movement includes operating sensordevice or camera 16, which is preferably, but not necessarily, mountedto the same casing 18 as display 12. The monitoring of eye movementpreferably also includes operating digital computer of microprocessor14, for instance, to carry out a pattern recognition process via patternrecognition module 40 and eye movement-tracking module 42 and to carryout a movement filtering process via fast eye velocity detection module32 and fast eye velocity calculation module 34. Computer or processor 14is also mounted to or housed in casing 18.

The parameter, magnitude or statistical value for the detected fast eyevelocity component may be determined by operating digital computer ormicroprocessor 14 and particularly calculation module 34 to carry outone or more arithmetic calculations. Where the selected parameter is eyemovement velocity, a calculation is of distance divided by time—avelocity calculation. The distance may be an angular distance or alinear distance.

Calculation module 34 may be configured to carry out additional oralternative measures of the fast eye movement component. For example,calculation module 34 may be programmed to compile a table of eyemovement amplitude as a function of eye velocity (or vice versa) and tocompute an average and a measure of the degree of uniformity ordeviation among the amplitudes or angular distances of the fast eyemovements. Alternatively, calculation module 34 might compile a table ofeye movement velocity as a function of amplitude or degree of eyemovement and compute a statistical measure such as degree of spread. Iffast eye velocity falls below 2 standard deviations (measure of spread)or variation of norms for any degree of movement, that can be taken asan indicator of potential brain trauma.

It is to be noted that the various modules of computer or microprocessor14 as shown in FIGS. 2 and 3 are realizable as generic digitalprocessing circuits that are configured through software to perform thedescribed functions. Alternatively, one or more of the various modulesof FIGS. 1-3 may be implemented in the form of hard-wired circuits. Thisis particularly the case with transceiver 24, stimulus generator 30, andfast eye movement detection unit 32.

One may also operate computer or microprocessor 14 and particularlycomparator 36 to ascertain whether the contemporaneously determined orcalculated fast eye velocity magnitude bears such a relation to apredetermined numerical value as to be indicative of minor (otherwiseundetectable) traumatic brain injury. Typically, if measured eyevelocity falls below a predetermined threshold, then possible braininjury is to be assumed.

As indicated above, the determining of the eye velocity magnitude may beimplemented at a remote station. In that event, eye movement data istransmitted over a computer network and a computed eye movement velocityis received in return over the computer network. The comparison ofcomputed eye movement velocity with the predetermined numerical valuemay also be performed at a remote location by another computer. In thatevent, the result of the comparison may be transmitted back to the onsite digital computer or microprocessor 14, either alone or togetherwith a computed magnitude of the fast eye velocity component.

Preferably, however, both the determination of eye velocity parameter,magnitude or statistic and the comparison with predetermined numericalreference value or threshold are automatically performed through theoperation of a programmed electronic device on site. This ensures thatan evaluation may be made at any time and any place, regardless ofaccess to a wireless or other network.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

1. A method for detecting minor traumatic brain injury, comprising:providing a device including an image generator, a sensor, and acomputer or microprocessor; operating said device and particularly saidimage generator to present to a subject a visual stimulus having apredetermined direction and speed of movement across a visual field ofthe subject; further operating said device and particularly said sensorto monitor movement of an eye of the subject while the subject viewssaid stimulus, the eye movement including a slow eye velocity componentresponsive to said predetermined movement, the eye movement furtherincluding a fast eye velocity component, the monitoring of eye movementincluding detecting said fast eye velocity component; additionallyoperating said device and particularly said computer or microprocessorto determine a parameter of the detected fast eye velocity component;and also operating said device and particularly said computer ormicroprocessor to compare the determined parameter with a predeterminedreference value to determine whether the subject has incurred minortraumatic brain injury.
 2. (canceled)
 3. The method defined in claim 1wherein said computer or microprocessor is operatively connected to saidsensor, the operating of said device and particularly said computer ormicroprocessor to determine said parameter including operating saiddevice to determine a numerical value for said parameter in response tomeasurements made via said sensor.
 4. The method defined in claim 3wherein said sensor is a camera taken from the group consisting of anoptical camera and an infrared camera.
 5. The method defined in claim 1wherein the operating of said device and particularly said computer ormicroprocessor to determine said parameter includes operating saidcomputer or microprocessor to carry out an arithmetic calculation. 6.The method defined in claim 5 wherein said sensor and said computer ormicroprocessor are housed in a casing, said casing being provided with adisplay, the operating of said device and particularly said imagegenerator to present said stimulus including operating said computer ormicroprocessor to provide said stimulus as a moving image on saiddisplay.
 7. The method defined in claim 6, further comprising removablyattaching said casing to a head of the subject prior to the presentingof said stimulus.
 8. (canceled)
 9. The method defined in claim 1 whereinthe operating of said device and particularly said computer ormicroprocessor to determine said parameter includes transmitting eyemovement data over a computer network and receiving at least onecomputed parametric value in return over said computer network. 10.(canceled)
 11. The method defined in claim 1 wherein the parameterincludes eye movement speed, the operating of said device andparticularly said computer or microprocessor to determine said parameterincluding measuring an amplitude or angular distance of eye movementduring at least one instance of said fast eye velocity component anddividing said amplitude or angular distance by the time or duration ofsaid one instance of said fast eye velocity component.
 12. The methoddefined in claim 1 wherein the operating of said device and particularlysaid computer or microprocessor to determine said parameter includesmeasuring an amplitude or angular distance of eye movement duringmultiple instances of said fast eye velocity component and determining adistribution of amplitudes, the determining of said parameter furtherincluding generating at least one statistical measure of saiddistribution of amplitudes.
 13. The method defined in claim 12 whereinthe predetermined reference value is a statistical reference value ofthe same kind as said statistical measure.
 14. The method defined inclaim 13 wherein the predetermined reference value is a measured valuepeculiar to the subject and derived from tests on the subject prior tophysical impact or trauma possibly giving rise to minor traumatic braininjury.
 15. The method defined in claim 1 wherein the operating of saiddevice and particularly said computer or microprocessor to determinesaid parameter includes operating said device and particularly saidcomputer or microprocessor to count instances of said fast eye velocitycomponent.
 16. An apparatus for detecting minor traumatic brain injury,comprising: generating means for presenting a visual stimulus having apredetermined movement across a visual field of a subject; sensing meansfor monitoring movement of an eye of the subject while the subject viewssaid stimulus, the eye movement including a slow eye velocity componentresponsive to said predetermined movement, the eye movement furtherincluding a fast eye velocity component, said sensing means beingconfigured to generate a signal encoding detected positions of thesubject's eye; and calculating means operatively connected to saidsensing means, said calculating means being configured for determining aparameter of the fast eye velocity component.
 17. The apparatus definedin claim 16 wherein said calculating means is further configured forcomparing said parameter with a predetermined reference value todetermine whether the subject has incurred minor traumatic brain injury.18. The apparatus defined in claim 16 wherein said calculating means isconfigured to measure an amplitude or angular distance of eye movementduring multiple instances of said fast eye velocity component anddetermine a distribution of amplitudes, as well as at least onestatistical measure of said distribution of amplitudes.
 19. Theapparatus defined in claim 16 wherein said sensing means is a camerataken from the group consisting of an optical camera and an infraredcamera.
 20. The apparatus defined in claim 16 wherein said sensing meansand said calculating means are housed in a casing, said casing beingprovided with a display, said calculating means being operativelyconnected to said display for operating said display to provide saidstimulus as a moving image on said display.
 21. The apparatus defined inclaim 20 wherein said casing has a hand-holdable configuration and size.22. The apparatus defined in claim 20, further comprising a headband orcap for removably attaching said casing to a head of the subject. 23.The apparatus defined in claim 16 wherein said calculating means isfurther configured for transmitting eye movement data over a computernetwork and receiving a computed result in return over said computernetwork.